2 replies to this topic

[aseem.kash]

hi!
I have completed the simulation of the vapor recovery unit and propylene recovery unit in aspen hysys V7.1
I am now suppose to do the heat integration of the 2 units
though I have decided the streams among which i need to exchange the heat but i am not aware of how to go about in hysys
if anyone could plz let me no d basic steps to proceed with this
thank you

[Zauberberg]

If you have identified the streams that are going to exchange the heat, further setup of the flowsheet shouldn't be that much difficult - just connect them using Heat Exchanger unit operation. One thing I would pay attention at, is to fix the temperature approach on all exchangers (e.g. 15-20 degC if S&T are used, 5-10 degC if Plate & Frame exchangers are used), since it should reflect something realistic.

If you want to go deeper into the world of heat exchanger networking and heat integration, see the links/documents below:

http://www.cheresour...m/pinchtech.pdf
http://www.ou.edu/cl...inhoffMarch.pdf

[Padmakar Katre]

hi!
I have completed the simulation of the vapor recovery unit and propylene recovery unit in aspen hysys V7.1
I am now suppose to do the heat integration of the 2 units
though I have decided the streams among which i need to exchange the heat but i am not aware of how to go about in hysys
if anyone could plz let me no d basic steps to proceed with this
thank you

Dear,
I consider that you already identified the hot-cold stream summary for your flow-sheet and even finalized the configuration i.e. how many exchangers (series/parallel)and what type of exchangers are to be used. Only what you need is to model those exchangers in Hysys so confirm your assumed configuration. If so follow what Zauberberg has suggested i.e. modeling the STHE or PHE(LNG Ex model)with the available hot and cold streams with reasonable temperature approaches. Once you are through with the modeling, if possible recall the STHEs in Aspen-HTFS design mode and confirm the given temperatures approach values are reasonable.
If you want to start from the scratch then first prepare the available hot-cold stream summary report with certain basic parameters as below,
1. Mass flow
2.Temperatures and final desired temperatures (e.g. in case of products storage temperature)
3.Pressures
4.Specific Heat,Cp
4.Thermal Conductivity
5.Viscosity

and start with preliminary configurations i.e. sequencing of heat exchangers and then detailed design i.e. type of HEx to meet the require objectives,in case of STHE-no of shells in series/parallel (if you need lower temperature approach values - shells in series would be more than 1 and for capacity control no of shells in parallel). You should check the enthalpy content and the temperature levels of each stream to decide which two streams to exchange with each other. I hope this helps you to solve your problem.

P.S.-Hysys will give you any temperature approach(+ve i.e. >0) but check is it economical to go for.